1. Technical Field
The present disclosure relates to a touch screen and, more particularly, to a monolithic haptic-type touch screen integrating a touch function and a haptic function, a manufacturing method thereof, and a display device including the same.
2. Background
A touch screen is an input device for recognizing a particular position when a user's hand or an object touches the particular position, and executing a particular function, without using an input device such as a keyboard or a mouse.
Touch screens are used in various display devices, for example, electronic products having various screen sizes, such as an automated teller (ATM) machine of a bank, a personal digital assistant (PDA), a portable multimedia player (PMP), a touch pad of a notebook computer, a navigation device, and the like, as well as a cellular phone.
Recently, beyond providing mere touch and direct manipulation functionality, haptic functionality has been added to the touch screen to provide touch sensation to users. Haptic technology is technology that allows users to feel the sense of touch, a force, a motion, and the like.
A haptic function is implemented together with a touch screen in a display device, and when a user touches a touch screen as an input device, the haptic function may provide a tactile feedback to the user through vibrations, or the like.
FIG. 1 is a view illustrating a structure of a related art display device including a touch screen and a haptic device.
Referring to FIG. 1, a related art display device 1 includes a cover glass 3, a touch screen 4, a display panel 2, and a haptic feedback unit 5.
The display panel 2 is a part where an image is substantially displayed, and an organic light emitting panel, a plasma panel, and the like, is used as the display panel 2.
The touch screen is positioned above the display panel 2 and senses a touch input applied by a user through the cover glass 3.
The touch screen 4 includes an insulating film 4b, and an upper electrode 4a and a lower electrode 4c respectively formed above and below the insulating film 4b. 
When the user applies a touch input through the cover glass 3, the touch screen 4 recognizes the touch input by capacitance generated between the upper electrode 4a and the lower electrode 4c, and performs a corresponding operation.
The cover glass 3 is positioned above the touch screen 4 to protect the touch screen 4 and the display panel 2. The cover glass 3 is formed as tempered glass having a predetermined thickness.
The haptic feedback unit 5 is positioned below the display panel 2 and provides a haptic feedback such as vibrations or the like, to the user.
The haptic feedback unit 5 operates together with the touch screen 4, and thus, when the user touches the touch screen 4, the haptic feedback unit 5 provides a haptic feedback to the user. The haptic feedback unit 5 is configured as a vibration motor or formed of piezoelectric ceramic.
Here, since the related art display device 1 having the foregoing configuration is configured to include the touch screen 4 and the haptic feedback unit 5, an overall thickness of the display device 1 increases.
Also, since the haptic feedback unit 5 is positioned in the lowermost portion, namely, below the display panel 2, haptics such as vibrations generated by the haptic feedback unit 5 may not properly be delivered to the user.
For example, in a case in which the haptic feedback unit 5 is configured as a vibration motor, it may be difficult to promptly provide a haptic feedback to the user due to a low response speed of the vibration motor, and in order to deliver uniform vibrations to the front surface of the display device, a large number of vibration motors should be used, which results in an increase in the thickness and size of the display device 1.
Also, in a case in which the haptic feedback unit 5 is formed of piezoelectric ceramic, a response speed may be enhanced, compared with the vibration motor, but manufacturing cost of the display device 1 increases due to high-priced piezoelectric ceramic. In addition, due to opaque characteristics of piezoelectric ceramic, the haptic feedback unit 5 needs to be disposed in the lowermost portion of the display panel 2, like the vibration motor, and thus, it is challenging to accurately deliver a haptic feedback to the user.